A flow that generates propulsive force or thrust occurs, for example, behind the propeller of a ship or an aircraft, behind the exhaust nozzle of an aero gas turbine, and under the rotor of a helicopter. The thrust is here effected by means of the velocity increment of the accelerated flow relative to the travel velocity, or flight velocity. It is greater, the higher the velocity increment, and the larger the flow cross-section. Here the thrust generation is itself always the result of utilization of a lift component of lifting bodies rotating approximately at right-angles to the flow about a common central axis, for example, propeller blades, rotor blades, or turbine blades. A simultaneous lift generation for purposes of compensating for the vehicle weight is, insofar as it is necessary—in the case of a ship's hull in water or an airship it is not necessary in general—only possible via additional equipment with a lifting wing, or the deflection of the direction of thrust by means of appropriate additional components, for example, pivoting propellers, or pivoting nozzles.
The application of these systems for the generation and/or control of thrust and lift experiences limitations, however, in a number of respects. Thus by means of the rotating lifting bodies a swirl is also imparted to the flow in addition to the desired deflection; this makes its presence felt in an unfavourable manner when utilizing the flow for the generation of thrust and/or lift.
Thus systems generating thrust and lift have already been developed that have as their prototype the device generating what is in general the best known symbiosis of lift and propulsive force, a bird's wing, and are of known art under the term “ornithopter” Articulated flapping wings, Nov. 21, 2006; Other flapping wing designs, Nov. 21, 2006; Basic methods for the twisting of flapping wings, Nov. 21, 2006; The principle of flight of ornithopter, Nov. 21, 2006). However, ornithopters have been unable to find any industrial scale applications up to the present time.
Also systems have already been developed that avoid the swirl cited above. Here these primarily take the form of systems that utilize the Knoller-Betz effect, in which these initiate and influence the flow by means of a streamline-shaped and usually symmetrical deflecting body transversely mounted and moved in the flow. Here the displacements of these deflecting bodies take place by means of pivoting movements about their transversely mounted (inside or outside the deflecting body) axis of rotation (all-moving tailplane principle) (DE 38 15 283 A1), and/or by an upward and downward movement by means of a hydraulic ram (DBP 1 025 275) or cables (DE 37 01 151 A1, annex to P 36 08 991.5).
It has also already been proposed for purposes of increasing both the pivoting frequency and the amplitude to allow the transversely supported pivot axis of the deflecting body to rotate in an eccentrically linked manner. Here the transversely mounted pivot axis then moves, so to speak, on the surface of a virtual cylinder rotating at right angles to the flow, and the profile chord of the deflecting body is held approximately parallel to the flow by means of a gearing mechanism. The best-known example of this type of drive is the wave propeller (W. Schmidt: The wave propeller, a new drive for water, land and air vehicles, Z. Flugwiss. 13 (1965), volume 12, pages 472-479 and DD 148 616). Here no form of thrust vector control is provided, and no utilization of lift forces for weight compensation is possible. Use of this drive is therefore preferably thought of in conjunction with a flow-smoothing profile body mounted downstream for pure thrust generation, as for example in the “Delphine airship” (U. Queck and W. Schmidt: Delphine of the air, Z. Flieger-Revue Jun. 1970, pages 226-233).
Thus it has also already been proposed to allow these deflecting bodies or the plurality of rotating deflecting bodies, as in the case of the wave propeller, to rotate between two parallel opposing discs eccentrically linked from their central axis transverse to the flow, but in addition during rotation also to activate individual members electronically via appropriate actuators in a systematic manner so as to generate an impulse in the direction of the desired thrust vector at all angles of rotation of the rotor (DE 42 17 374 and DE 43 20 625 A1). Up to the present time there have been no practical implementations of this drive of known art. Only one mechanical solution as a special form of this type of thrust vector control is of known art as the Voith-Schneider propeller, limited to ships' drives.
Furthermore a modified wave propeller drive with a downstream profile body has been proposed, which is intended to pivot as a complete unit, so as to thereby enable vector control (DD 300 703 A7).
Furthermore a light aircraft with a manual drive of a flapping wing guided in a semicircular shape is of known art; this is intended to generate the lift in addition to the propulsive force (DD 292 186 A5).
What is disadvantageous in the drive units that have been so far presented is on the one hand their efficiency, which is usually too low as a result of too low a flapping frequency, their limitation to the generation of thrust, and an achievement of a good efficiency that is limited to particular ranges of rotational speed. Furthermore, the rotating systems have a reduced efficiency as a result of the ineffective phases during the circular movement of the deflecting body, or bodies, which become apparent in the segment of rotation in which they are retreating (similar to those phases occurring in the case of a helicopter rotor), as well as a cyclically-fluctuating separation distance from the vehicle body.
Moreover, the lift-generating surface area of the individual deflecting bodies (at least in the case of a multiple arrangement) in the wave rotor is far smaller, because both the profile chord is limited, and thus also the profile thickness, and so for reasons of strength the span also.
Also by virtue of the circle of rotation a relatively large lever arm for the linkage of these drives to the vehicle body/aircraft fuselage is disadvantageous in terms of weight, forces and moments.